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Abstract
The magnetic activity of late-type stars is correlated with their
rotation rates. Up to a certain limit, stars with smaller Rossby
numbers, defined as the rotation period divided by the convective
turnover time, have higher activity. A more detailed look at this
rotation-activity relation reveals that, rather than being a simple
power law relation, the activity scaling has a shallower slope for the
low-Rossby stars than for the high-Rossby ones. We find that, for the
chromospheric CaII H&K activity, this scaling relation is well
modelled by a broken two-piece power law. Furthermore, the knee-point of
the relation coincides with the axisymmetry to non-axisymmetry
transition seen in both the spot activity and surface magnetic field
configuration of active stars. We interpret this knee-point as a dynamo
transition between dominating axi- and non-axisymmetric dynamo regimes
with a different dependence on rotation and discuss this hypothesis in
the light of current numerical dynamo models.
Original language | English |
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Article number | 110 |
Number of pages | 8 |
Journal | The Astrophysical Journal |
Volume | 910 |
Issue number | 2 |
DOIs | |
Publication status | Published - 1 Apr 2021 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Astrophysics - Solar and Stellar Astrophysics
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Dive into the research topics of 'A Knee-Point in the Rotation-Activity Scaling of Late-type Stars with a Connection to Dynamo Transitions'. Together they form a unique fingerprint.Projects
- 1 Finished
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UniSDyn: Building up a Unified Theory of Stellar Dynamos
Korpi-Lagg, M. (Principal investigator), Pekkilä, J. (Project Member), Rheinhardt, M. (Project Member), Weigt, D. (Project Member), Gent, F. (Project Member) & Gozaliasl, G. (Project Member)
01/01/2020 → 30/04/2024
Project: EU: ERC grants